The goal of secondary prevention is to detect and treat a disease at its pre-clinical stage so as to prevent significant mortality or morbidity associated with late-stage disease. The benefit of secondary prevention can only be achieved if patients receive effective treatment following the diagnosis of a disease. Therefore, a discussion of the cost-effectiveness of secondary prevention strategies shall take into consideration the treatment aspect of a disease. Such consideration is also important for resource allocation because the cumulative cost of secondary prevention to the health care system can be substantial due to the large population involved in a screening intervention and the repetitive nature of screening exams over time. Our proposed study will explore the economics of secondary prevention by examining the association between the diffusion of treatment technologies and the cost-effectiveness of secondary prevention. Using screening mammography for women age 65 as an example, we will explore the above association and estimate the impact of various screening strategies on Medicare expenditures under different scenarios of treatment dissemination. Screening mammography strategies to be evaluated will consist of a combination of difference screening intervals (annual, biennial, and triennial) and cessation ages (75, 80, 85, and no upper age limit). We will consider two approaches to improve the treatment of breast cancer: (a) better dissemination of prevailing treatments through the use of risk assessment tools and (b) adoption of newly approved efficacious treatments. The base case scenario of treatment dissemination will be based on the actual population-based treatment pattern of older women diagnosed with breast cancer as observed in the SEER- Medicare database. We will extend a previously developed microsimulation model to conduct the proposed cost-effectiveness and budgetary impact analyses. To make the findings of our study directly applicable to decision makers at the Centers for Medicare and Medicaid Services (CMS), the study perspective will be that of Medicare. The benefit associated with each screening mammography strategy will be measured by the life-years saved and the quality-adjusted life-years gained. Costs to be estimated in the proposed study include those of the interventions, management of adverse events, breast cancer treatments after diagnosis, etc. The focus on old women will allow us to evaluate Medicare's current coverage of screening mammography and provide information to policy makers at the CMS to understand the clinical as well as economic benefits and risks associated with various combinations of screening and treatment patterns. Findings from our study will facilitate health policy recommendations of effective and cost-effective secondary prevention strategies and provide guidance on how to allocate the limited resource for an affordable and sustainable health care system.